Light-emitting keyboard and backlight module

ABSTRACT

A light-emitting keyboard includes a bracket, a keycap, a circuit layer, a composite light-emitting layer and a spacing layer. The bracket has an opening. The keycap is disposed on the bracket and connected to the bracket via a support assembly. The circuit layer is disposed between the keycap and the bracket. The composite light-emitting layer is disposed under the bracket, and includes a substrate, a circuit disposed on the substrate and a light source located under the keycap and electrically connected to the circuit, wherein light emitted from the light source is transmitted upwardly to the keycap. The spacing layer is disposed between the composite light-emitting layer and the bracket, wherein the spacing layer includes a hole corresponding to the opening of the bracket, and the light source is located in the hole of the spacing layer.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation-in-part application of and claims the priority benefit of U.S. application Ser. No. 16/528,592, filed on Jul. 31, 2019, now allowed, which claims the priority benefits of U.S. provisional application Ser. No. 62/712,993, filed on Aug. 1, 2018, and China application serial no. 201910623300.8, filed on Jul. 11, 2019. The entirety of each of the above-mentioned patent applications is hereby incorporated by reference herein and made a part of this specification.

BACKGROUND OF THE INVENTION Field of the Invention

The invention relates to a backlight module and a light-emitting keyboard, and more particularly to an ultra-thin backlight module and light-emitting keyboard.

Description of Related Art

With the development of technology, the appearance of electronic products tends to be lighter and thinner, and creating visual interest is an upward trend. Taking buttons as an example, light-emitting buttons have been designed to increase aesthetics or recognizability. In the light-emitting button, a backlight module is mainly provided under a button structure, and how to make the backlight module provide various optical effects or slim down the backlight module is the latest research direction.

SUMMARY OF THE INVENTION

The invention provides a backlight module having a scaled-down thickness.

A light-emitting keyboard of the invention can display various backlighting effects.

A light-emitting keyboard includes a bracket, a keycap, a circuit layer, a composite light-emitting layer and a spacing layer. The bracket has an opening. The keycap is disposed on the bracket and connected to the bracket via a support assembly. The circuit layer is disposed between the keycap and the bracket. The composite light-emitting layer is disposed under the bracket, and includes a substrate, a circuit disposed on the substrate and a light source located under the keycap and electrically connected to the circuit, wherein light emitted from the light source is transmitted upwardly to the keycap. The spacing layer is disposed between the composite light-emitting layer and the bracket, wherein the spacing layer includes a hole corresponding to the opening of the bracket, and the light source is located in the hole of the spacing layer.

In an embodiment of the invention, a top surface of the spacing layer is higher than a top surface of the light source.

In an embodiment of the invention, a top surface of the light source is located within the opening, and the top surface of the light source is lower than a top surface of the bracket.

In an embodiment of the invention, the light-emitting keyboard further includes a first light-reflecting coating and a first light-shielding coating, the substrate is a light-transmitting substrate, the light source and the circuit are disposed on an upper surface of the substrate, the first light-reflecting coating is disposed on a lower surface of the substrate, and the first light-shielding coating is disposed under the first light-reflecting coating.

In an embodiment of the invention, the light-emitting keyboard further includes a second light-shielding coating disposed between the spacing layer and the bracket, wherein the keycap includes a bottom plate and a plurality of side plates protruding from the bottom plate, the second light-shielding coating is a frame shape corresponding to the side plates of the keycap.

In an embodiment of the invention, the light-emitting keyboard further includes a second light-reflecting coating disposed on a top surface of the spacing layer, wherein the second light-shielding coating is disposed on a portion of the second light-reflecting coating, the second light-reflecting coating is surrounded by the second light-shielding coating.

In an embodiment of the invention, the spacing layer is a light-shielding plate, a second light-reflecting coating is disposed on a top surface of the spacing layer, and the second light-reflecting coating is located within a coverage of the keycap.

In an embodiment of the invention, the spacing layer is a light guide plate, and a plurality of microstructures is arranged on a surface of the spacing layer.

In an embodiment of the invention, the spacing layer is an encapsulation layer, and a passivation layer is disposed on the spacing layer and the light source.

In an embodiment of the invention, the light-emitting keyboard further includes a connection tail, wherein the foldable connection tail is partially disposed on the substrate and electrically connected to the circuit.

In an embodiment of the invention, the connection tail includes a circuit layer facing the circuit of the composite light-emitting layer and being made of a material with a different conductivity from the circuit, and the circuit layer is electrically coupled to the circuit through a conductive adhesive.

In an embodiment of the invention, the circuit includes a first circuit electrically connected to the light source and a second circuit electrically connected to the first circuit and coupled to another light source corresponding to an adjacent keycap, and a material of the first circuit is different from a material of the second circuit.

A backlight module adapted to be disposed under a button structure, wherein the backlight module includes a composite light-emitting layer including a light source and a first circuit disposed on a first side of the light-transmitting substrate, and a passivation layer covering the first circuit and the light-transmitting substrate, wherein the light source is coupled to the first circuit, and light emitted from the light source is adapted to be transmitted upwardly to the button structure; and a spacing layer disposed on the composite light-emitting layer, wherein the spacing layer includes a hole, and the light source is located in the hole of the spacing layer.

In an embodiment of the invention, a thickness of the spacing layer is greater than or equal to a thickness of the light source.

In an embodiment of the invention, a thickness of the spacing layer is less than a thickness of the light source such that a portion of the light source extends into an opening of the button structure.

In an embodiment of the invention, the backlight module further includes a first light-reflecting coating and a first light-shielding coating disposed on a second side of the substrate, wherein the first light-reflecting coating is arranged between the first light-shielding coating and the substrate.

In an embodiment of the invention, the backlight module further includes a second light-shielding coating disposed on a top surface of the spacing layer facing the button structure, wherein a shape of the second light-shielding coating is a frame shape exposing the light source.

In an embodiment of the invention, the backlight module further includes a second light-reflecting coating and a second light-shielding coating, wherein the second light-reflecting coating is disposed on a top surface of the spacing layer, the second light-shielding coating is disposed on the top surface of the spacing layer and stacked on a portion of the second light-reflecting coating, a shape of the second light-shielding coating is a frame shape, at least a portion of a projection of the second light-reflecting coating projected onto the spacing layer overlaps with a projection of the second light-shielding coating projected onto the spacing layer.

In an embodiment of the invention, the spacing layer is a light-shielding plate, a second light-reflecting coating is disposed on a top surface of the spacing layer, and a projection of the second light-reflecting coating is located adjacent to the hole.

In an embodiment of the invention, the spacing layer is a light guide plate, and a plurality of microstructures is arranged on a top surface or a bottom surface of the spacing layer.

In an embodiment of the invention, the spacing layer is an encapsulation layer made of a transparent or translucent resin.

In an embodiment of the invention, the composite light-emitting layer further includes a second circuit electrically connected to the first circuit and extended outwardly, wherein the first circuit and the second circuit are made of materials with different conductivities.

In an embodiment of the invention, the backlight module further includes a connection tail, wherein the connection tail is partially disposed on the substrate and electrically connected to the second circuit through a conductive adhesive, and the connection tail is folded from an upper surface of the substrate to a lower surface of the substrate.

Based on the above, the backlight module and the light-emitting keyboard of the invention includes the light source located under the keycap, and the light source is located in the hole of the spacing layer, so that the light source and the spacing layer are located at the same level, the light-emitting keyboard and the backlight module could be miniaturized in thickness. In addition, because light emitted from the light source is transmitted upwardly to the keycap, the optical path of the light source directly illuminate the button structure to provide a localized backlighting effect to the individual buttons.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide a further understanding of the invention, and the drawings are incorporated into the present specification and form a portion of the present specification. The drawings illustrate embodiments of the invention and are used to explain the principles of the invention with the descriptions.

FIG. 1A is a top view of a light-emitting keyboard according to an embodiment of the invention.

FIG. 1B is an exploded view of a backlight module of the light-emitting keyboard of FIG. 1A.

FIG. 1C is a partial cross-sectional view of the button structure with the backlight module of FIG. 1B disposed thereunder.

FIG. 2A is an exploded view of a backlight module according to another embodiment of the invention.

FIG. 2B is a partial cross-sectional view of the backlight module of FIG. 2A.

FIG. 2C is a partial view of the composite light-emitting layer of the backlight module of FIG. 2A.

FIG. 2D is a diagram showing the positional relationship between a first light source, a first circuit, and a bracket of a button structure of the backlight module of FIG. 2A.

FIG. 3 is a partial cross-sectional view of a backlight module according to another embodiment of the invention.

FIG. 4A is an exploded view of a backlight module according to another embodiment of the invention.

FIG. 4B is a partial cross-sectional view of the backlight module of FIG. 4A.

FIG. 4C is a cross-sectional view of another portion of the backlight module of FIG. 4A.

FIG. 5 to FIG. 7 are partial cross-sectional views of various backlight modules according to other embodiments of the invention.

FIG. 8 is a partial cross-sectional view of the button structure with a backlight module according to another embodiment of the invention.

FIG. 9 is a projecting view of the light source, the bracket and the first light-shielding coating projected onto the keycap of FIG. 8.

FIG. 10 to FIG. 15 are partial cross-sectional views of the button structure with various backlight modules according to another embodiment of the invention.

FIG. 16 to FIG. 17 are partial cross-sectional views of various backlight modules according to other embodiments of the invention.

FIG. 18 is a projecting view of the light source, the first circuit, the second circuit and the first light-shielding coating projected onto the keycap of the button structure with a backlight module according to another embodiment of the invention.

FIG. 19 is a partial cross-sectional view along A-A section of the light source, the first circuit, the second circuit of FIG. 18.

DESCRIPTION OF THE EMBODIMENTS

Hereinafter, exemplary embodiments of the invention are described in detail, and examples of the exemplary embodiments are conveyed via the figures. Wherever possible, the same reference numerals are used in the figures and the descriptions to refer to the same or similar portions.

FIG. 1A is a top view of a light-emitting keyboard according to an embodiment of the invention. FIG. 1B is an exploded view of a backlight module of the light-emitting keyboard of FIG. 1A.

Referring to FIG. 1A and FIG. 1B, a light-emitting keyboard 5 of the present embodiment includes at least one button structure 10 and a backlight module 100 located under the button structure 10. Light provided by the backlight module 100 illuminates the rear side of the button structure 10 to provide the user with an identification or various visual effects. The light-emitting keyboard 5 shown in FIG. 1A is exemplified by, for example but not limited to, a keyboard of a notebook computer.

FIG. 1C is a partial cross-sectional view of the button structure with the backlight module of FIG. 1B disposed thereunder. It should be noted that, in order to clearly show the detailed structure of the backlight module, only a single button structure 10 is schematically shown in FIG. 1C, and the relationship in size of elements included in the button structure 10 and the backlight module 100 is only for schematic illustration.

As shown in FIG. 1C, in the present embodiment, the button structure 10 includes a keycap 11, a support assembly 12, an elastic body 13, a circuit layer 14, and a bracket 15. The bracket 15 is disposed on the backlight module 100 for holding the keycap 11, the support assembly 12, the elastic body 13, and the circuit layer 14 in position. The bracket 15 may have a plurality of openings (such as through holes) that allow light to pass through or to accommodate a light source. For example, the rear surface of the keycap 11 may be illuminated by the light from the backlight module 100 via openings 16 and 18, and the opening 16 may accommodate a first light source 140 of the backlight module 100 as well. The number and arrangement of the openings of the bracket 15 are not limited to the disclosure.

The circuit layer 14 is disposed between the keycap 11 and the bracket 15. The circuit layer 14 is, for example, a flexible membrane circuit in a multi-layered structure having a conductive portion 17 as a switching region to trigger signals. The elastic body 13 is disposed between the keycap 11 and the circuit layer 14, and provides a restoring force to drive the keycap 11 move up and return to its released state. The support assembly 12 is disposed between the keycap 11 and the bracket 15. The respective ends of the support assembly 12 are pivotably and movably connected to the keycap 11 and the bracket 15, such that the keycap 11 is stably moved up and down relative to the bracket 15 via the connection of the support assembly 12. The support assembly 12 is, for example but not limited to, a scissor-like mechanism that includes two supporting pieces pivotally assembled together.

The elastic body 13 is located on the circuit layer 14 corresponding to the conductive portion 17, wherein the elastic body 13 has a protrusion aligned with and disposed above the conductive portion 17. When the keycap 11 is pressed to temporarily squeeze and deform the elastic body 13, the protrusion of the elastic body 13 moves downward to press the conductive portion 17 of the circuit layer 14, such that the switch is turned on to generate an input signal. Once the applied force is removed from the keycap 11, the restoring force of the elastic body 13 drives the keycap 11 to move upward and return to the inactive (unpressed) position. In the present embodiment, the keycap 11 may have a light-transmitting portion 11 a defined by, for example, at least one character represented by each button structure 10 to allow the light emitted by the backlight module 100 to pass through, and thus a light-emitting button is obtained for user identification.

The backlight module 100 under the button structure 10 includes a light-reflecting plate 110, a light guide plate 120, and a composite light-emitting layer 130 stacked from the bottom upwards to the top. The composite light-emitting layer 130 is disposed between the bracket 15 and the light guide plate 120, and the light guide plate 120 is disposed between the composite light-emitting layer 130 and the light-reflecting plate 110. As shown in FIG. 1B, the composite light-emitting layer 130 located on the light guide plate 120 has a light-shielding pattern 133 which may shade the regions that do not need to be illuminated by light, thereby avoiding light leakage. The composite light-emitting layer 130 is provided with a light-transmitting region 138 where the light-shielding pattern 133 does not cover, and the light can pass through the light-transmitting region 138 to backlight the button. In an embodiment, in order to avoid light leakage between the button structures 10, the light-shielding pattern 133 may be disposed under the gap between two adjacent keycaps 11, and the light-transmitting region 138 could be surrounded by the light-shielding patterns 133. The light-transmitting region 138 is positioned corresponding to the keycap 11, so that the light could be delivered to the button structure 10 of the light-emitting keyboard 5 (FIG. 1A).

In the present embodiment, the composite light-emitting layer 130 includes a light-transmitting substrate 131, and a light-shielding plate 134 located under the light-transmitting substrate 131. A first circuit 139, the first light source 140, and a first passivation layer 142 are arranged on the light-transmitting substrate 131. The first circuit 139 and the first light source 140 are disposed on one side of the light-transmitting substrate 131, and the first light source 140 is electrically connected to the first circuit 139. The first circuit 139 includes a printed conductive paste or a patterned metal layer, such as printed silver wiring or a patterned copper foil, but the type of the first circuit 139 is not limited thereto. After the first circuit 139 is formed on the upper surface of the light-transmitting substrate 131, the first light source 140 is disposed on the upper surface of the light-transmitting substrate 131, such that electrodes of the first light source 140 are electrically connected to the first circuit 139. The light-transmitting substrate 131 and the first circuit 139 thereon are collectively used as a circuit board that supplies power to the first light source 140. The first passivation layer 142 covers the first circuit 139, such that at least a portion of the first circuit 139 is located between the first passivation layer 142 and the light-transmitting substrate 131, thereby preventing an open circuit or a short circuit caused by the damaged circuit pattern on the light-transmitting substrate 131. In an embodiment, the first passivation layer 142 may further cover the first light source 140 to protect both of the first circuit 139 and the first light source 140. The first passivation layer 142 is, for example, a flexible polymer film having a thickness less than the thickness of the light-transmitting substrate 131.

As shown in FIG. 1B and FIG. 1C, the light-shielding plate 134 is located between the light guide plate 120 and the light-transmitting substrate 131, and the light-transmitting region 138 is defined, by the light-shielding pattern 133, on the light-shielding plate 134. The light-shielding plate 134 includes a film 135 and the light-shielding pattern 133 formed on the surface of the film 135. In the present embodiment, the film 135 is a light-transmitting substrate, and the light-shielding pattern 133 includes a light-reflecting coating 136 and a light-shielding coating 137 layered on one side of the light-transmitting substrate. If the light travelling in the light guide plate 120 is incident on the light-shielding pattern 133, the light could be reflected back into the light guide plate 120 by the light-reflecting coating 136, while the light-shielding coating 137 could prevent the light from being emitted out of the light-shielding pattern 133. In an embodiment, the light-reflecting coating 136 is a white paint, and the light-shielding coating 137 is a black paint. The structural configuration of the light-shielding pattern 133, and the colors of the light-reflecting coating 136 and the light-shielding coating 137 are not limited to the disclosure.

The first light source 140 is disposed on the surface of the light-transmitting substrate 131 distal to the light-shielding plate 134. In the present embodiment, the light-transmitting substrate 131 has its lower surface facing toward the light-shielding plate 134, and the first light source 140 is situated on the upper surface of the light-transmitting substrate 131 and functions as, for example, a top-view light source. The first light source 140 is disposed in the opening 16 of the bracket 15 corresponding to the light-transmitting portion 11 a of the keycap 11, and therefore the first light source 140 does not protrude from the upper surface of the bracket 15. Thus, the light emitted by the first light source 140 under the button is adapted to upwards and directly illuminate the button structure 10 a direction away from the light-shielding plate 134 so as to provide a directionally backlighting effect, thereby achieving independent light emission for a single button. In other embodiments, the stacking positions of the light-shielding plate 134 and the light-transmitting substrate 131 could be changed, such that the light-shielding plate 134 may be located between the bracket 15 and the light-transmitting substrate 131 having the light emitted from the first light source 140 not blocked by the light-shielding plate 134.

The backlight module 100 further includes a circuit board 150 and a second light source 160. The circuit board 150 is located under the light-reflecting plate 110. A portion of the light-reflecting plate 110 is disposed between the circuit board 150 and the light guide plate 120. The circuit board 150 is, for example, a flexible circuit board coupled to a power supply providing power to the second light source 160. The second light source 160 is disposed under the composite light-emitting layer 130, and is electrically coupled to the circuit board 150 through penetrating the light guide plate 120 and the light-reflecting plate 110. For example, the light-reflecting plate 110 and the light guide plate 120 are respectively provided with openings 114 and 126 in which the second light source 160 is disposed, such that the second light source 160 positioned on the circuit board 150 could go upward and be next to one side of the light guide plate 120. The second light source 160 is, for example, a side-view light source that could emit light toward the lateral side of the light guide plate 120. The light emitted by the second light source 160 is adapted to enter the light guide plate 120 and travel over the interior thereof compliant with total reflection, such that the light could be uniformly and evenly distributed throughout the entire backlight module 100 and emitted out from the light-transmitting region 138 of the light-shielding plate 134 to provide an optical effect of enhanced uniformity.

The first light source 140 and the second light source 160 may be light-emitting diodes respectively in different types or packages. In the present embodiment, the first light source 140 could be a chip-scale packaged LED without leadframe or substrate, wherein a LED chip or die is disposed on the light-transmitting substrate 131 in a flip-chip manner, and the respective electrodes of the LED die are connected to the first circuit 139 via a soldering or surface-mounting technique. Optionally, dispensing of gel with phosphor, if phosphor conversion is required, may be performed on the LED die, such that the light-transmitting encapsulation (e.g., light-curable resin with or without phosphor) covers the die for protection and/or light conversion. Compared with the leadframe-based LED with the thickness of about 0.6 mm, the miniaturized first light source 140 of the present embodiment adopts a chip-scale package without additional substrate and wire bonding, and therefore, the thickness of the first light source 140 could be thinned to 0.08 mm or less. Moreover, the circuit for the first light source 140 is made from a printed conductive paste or a patterned metal foil, which is much thinner than an ordinary circuit board (about 0.15 mm to 0.2 mm). Therefore, the backlight module 100 could be slimmed down by integrating the first light source 140 into the composite light-emitting layer 130. It should be noted that the thicknesses of the components shown in the figures only illustrate the relationship in position and thickness, which are not limited thereto.

In the present embodiment, the second light source 160 of the backlight module 100 is, for example, a side-view light source, and the backlight module 100 could evenly and uniformly illuminate the buttons of the light-emitting keyboard 5 via the second light source 160, the light-reflecting plate 110, and the light guide plate 120. In addition, the first light source 140 of the backlight module 100 is, for example, a top-view light source. For a button having a special function (e.g., hot keys) of the light-emitting keyboard 5, the backlight module 100, via the first light source 140, may provide localized backlighting which is independently adjustable for the special hot keys, thereby allowing users to quickly identify this button in a visual manner.

The configuration of the backlight module of the invention is not limited to the backlight module 100. The following embodiments would elaborate other types of backlight modules. Except for the major difference, the same or similar components as those of the previous embodiment are represented by the same or similar reference numerals and are not repeated hereinafter. In order to clearly show the detailed structure of the backlight modules, the button structure is not shown in some figures, but it should be understood that the backlight modules of the following embodiments are adapted to be disposed under the button structure to provide a button backlit effect.

FIG. 2A is an exploded view of a backlight module according to another embodiment of the invention. FIG. 2B is a partial cross-sectional view of the backlight module of FIG. 2A. Referring to FIG. 2A and FIG. 2B, in the present embodiment, a composite light-emitting layer 130 a of a backlight module 100 a includes the light-shielding plate 134 disposed on the light guide plate 120, and the first circuit 139 disposed on the light-shielding plate 134. The first light source 140 is disposed on the light-shielding plate 134 and electrically connected to the first circuit 139. That is, the light-shielding plate 134 and the first circuit 139 thereon are collectively used as a circuit board for the first light source 140. Compared with the embodiment shown in FIG. 1B and FIG. 1C, the light-transmitting substrate 131 of the composite light-emitting layer 130 is no longer required in the composite light-emitting layer 130 a of the present embodiment, such that the overall thickness of the composite light-emitting layer 130 a may be reduced. The first circuit 139, the first light source 140, and the first passivation layer 142 previously on the light-transmitting substrate 131 shown in FIG. 1C are modified, in the present embodiment, to be directly disposed on the surface of the film 135 (such as the light-transmitting substrate) of the light-shielding plate 134.

In the present embodiment, the first light source 140 and the light guide plate 120 are located on two opposite sides of the light-transmitting film 135. The first light source 140 is disposed on the upper side of the light-shielding plate 134, while the light guide plate 120 is disposed on the lower side of the light-shielding plate 134; that is, the first light source 140 is disposed on the surface of the light-shielding plate 134 distal to the light guide plate 120. When the button structure is combined with the backlight module 100 a, the opening 16 of the bracket 15 shown in FIG. 1C may be used as the accommodating space for the first light source 140, and the light emitted by the first light source 140 illuminates toward a direction opposite to the light guide plate 120 to provide the individual button with the independent and directional backlighting. The light emitted by the second light source 160 is adapted to enter the light guide plate 120 to provide an optical effect with uniform brightness, as depicted in the above embodiment.

In addition, in the composite light-emitting layer 130 a, the first circuit 139 disposed on the light-shielding plate 134 could be electrically connected to the circuit board 150. The first circuit 139 laid out at an end 132 of the composite light-emitting layer 130 a is, for example, coupled to the circuit of the circuit board 150 via a soldering or hotbar bonding. That is to say, even if the first light source 140 and the second light source 160 are located on different layers, the interconnection therebetween could be conducted via the circuit board 150, such that the single supply power could provide power to the first light source 140 and the second light source 160. Accordingly, the circuit design can be simplified, and the respective light emission of the first light source 140 and the second light source 160 could be independently controlled as well. In other embodiments, the first light source 140 and the second light source 160 may be connected to different power supplies; that is, the first circuit 139 of the first light source 140 may not be connected to the circuit board 150.

FIG. 2C is a partial view of the composite light-emitting layer of the backlight module of FIG. 2A. FIG. 2D is a diagram showing the positional relationship between a first light source, a first circuit, and a bracket of a button structure of the backlight module of FIG. 2A. Referring to FIG. 2C, the first light source 140 corresponding to the single button structure is located at a position corresponding to the light-transmitting region 138, and the first circuit 139 coupled to the first light source 140 is distributed along the light-shielding pattern 133 on the light-shielding plate 134. Referring to FIG. 2D, in the present embodiment, the first light source 140 is located within the range corresponding to the opening 16 of the bracket 15 and corresponding to the light-transmitting portion 11 a of the keycap 11. The majority of the first circuit 139 is located at a position outside the projection of the keycap 11, while a portion of the first circuit 139 under the keycap 11 is arranged at a position corresponding to the bracket 15 where the openings 16 and 18 are not formed (i.e., the non-opening region of the bracket 15). Thus, the layout of the first circuit 139 may be hidden under the bracket 15. Since the first circuit 139 of the composite light-emitting layer 130 a is arranged corresponding to the main body of the bracket 15 to avoid the openings 16 and 18, the first circuit 139, for the user, could be invisible through the light-transmitting region 138 and barely impact the optical effects.

As shown in FIG. 2C and FIG. 2D, the first light source 140 may include a plurality of light-emitting diodes 143, 144, and 145. In an embodiment, the light-emitting diodes 143, 144, and 145 emit light of different wavelengths, such as red, green, and blue, but are not limited thereto. The light-emitting diodes 143, 144, and 145 are respectively connected to three separate circuit layouts (collectively referred to as the first circuit 139), such that the light-emitting states of the light-emitting diodes 143, 144, and 145 may be individually and independently controlled, thus achieving combinations of single-color light emission or mixed light emission. That is, a plurality of light-emitting diodes having different colors (collectively referred to as the first light source 140) are disposed under a single button, and the keycap 11 could exhibit various backlighting effects.

FIG. 3 is a partial cross-sectional view of a backlight module according to another embodiment of the invention. Referring to FIG. 3, the major difference between a backlight module 100 b of FIG. 3 and the backlight module 100 a of FIG. 2B is that, in the present embodiment, the first circuit 139 is connected to the circuit board 150 via a connector 152. The film 135 and the first circuit 139 thereon may be easily inserted into the connector 152 coupled to the circuit layout of the circuit board 150 at the end 132 of the composite light-emitting layer 130 a to be electrically connected to the circuit board 150. It should be noted that the circuit board 150, as depicted in FIG. 3, is a single-layer circuit board, and the connector 152 is disposed under the circuit board 150 in a folding manner to connect the end 132 of the first circuit 139. In other embodiments, the circuit board 150 may be a double-layer circuit board, and the connector 152 may be directly mounted on the lower surface of the circuit board 150 without folding the circuit board 150.

FIG. 4A is an exploded view of a backlight module according to another embodiment of the invention. FIG. 4B is a partial cross-sectional view of the backlight module of FIG. 4A. Referring to FIG. 4A and FIG. 4B, in the present embodiment, the first light source 140 and the light guide plate 120 of a backlight module 100 c are located on the same side of the light-transmitting substrate (i.e., the film 135). The light guide plate 120 has a hole 122, and the first light source 140 is disposed on the surface of the light-shielding plate 134 facing the light-reflecting plate 110 and corresponding to the hole 122. The first light source 140 could be arranged in the hole 122 or disposed on the periphery of the hole 122. The light emitted by the first light source 140 is adapted to enter the light guide plate 120, be reflected by the light-reflecting plate 110, and then be emitted through the light-transmitting region 138. In addition, the first light source 140 on the light-shielding plate 134 is disposed at a position corresponding to the light-shielding pattern 133, such that the light of the first light source 140 could be reflected back into the light guide plate 120 by the light-reflecting coating 136 and be uniformly distributed over the entire light guide plate 120, and leakage from the light-shielding coating 137 may be prevented as well.

In the present embodiment, light emission toward the light guide plate 120 by the side-view light source may be achieved by the first circuit 139 and the first light source 140 disposed on the light-shielding plate 134, so as to obtain the light path similar to the second light source 160 shown in FIG. 2A and FIG. 2B. Therefore, the flexible circuit board 150 and the second light source 160 of FIG. 2A and FIG. 2B are not required for the backlight module 100 c of the present embodiment, thereby reducing the thickness thereof. That is to say, the first light source 140 of the present embodiment does not function as independent backlighting for a single button, but replaces the side-view light source to make the light emitted by the first light source 140 enter the light guide plate 120, such that a backlighting effect with uniform and even brightness could be obtained via the first light source 140.

FIG. 4C is a partial cross-sectional view of a backlight module according to another embodiment of the invention. Referring to FIG. 4C, in the present embodiment, a composite light-emitting layer 130 c 1 of a backlight module 100 c 1 is disposed under the light guide plate 120 and may be used as a light-reflecting plate of the backlight module 100 c 1. Since the bracket of the button structure is disposed above the backlight module 100 c 1, the light guide plate 120 is disposed between the bracket and the composite light-emitting layer 130 c 1. The light-shielding plate 134 may be further disposed above the light guide plate 120. The light emitted by the composite light-emitting layer 130 c 1 under the light guide plate 120 is adapted to enter the interior of the light guide plate 120 and to be distributed over the light guide plate 120, until the light is emitted out from the top surface of the light guide plate 120 not covered by the light-shielding coating 137 and emitted toward the button structure.

The composite light-emitting layer 130 c 1 includes a light-transmitting substrate 111, and a first circuit 112, a first light source 170, and a first passivation layer 172 disposed on the light-transmitting substrate 111. The first light source 170 is electrically connected to the first circuit 112. The first circuit 112, the first light source 170, and the light guide plate 120 are located on the same side (such as the upper surface) of the light-transmitting substrate 111. The light guide plate 120 has a hole 123, and the first light source 170 on the light-transmitting substrate 111 is disposed at a position corresponding to the hole 123. In an embodiment, the first light source 170 is arranged in the hole 123 or is located on the periphery of the hole 123. The first passivation layer 172 covers the first circuit 112 to prevent the damaged circuit pattern for the first light source 170. The first passivation layer 172 may be a light-reflecting coating (such as white paint) or a light-reflecting polymer film, which could reflect light back into the light guide plate 120 and prevent the first circuit 112 layout from affecting the optical effects of the backlight module 100 c 1.

The first light source 170 is, for example, exposed outside the first passivation layer 172 to prevent the first passivation layer 172 from shading the light emitted from the first light source 170 and interfering the light coupling of the light guide plate 120. In addition, the lower surface of the light-transmitting substrate 111 is provided with a light-shielding coating 117 as a light-shielding pattern of the composite light-emitting layer 130 c 1. The light-shielding coating 117 and the first light source 170 are located on opposite sides of the light-transmitting substrate 111. The light-shielding coating 117 is, for example, fully coated on the lower surface of the light-transmitting substrate 111 to prevent the light leakage from the bottom of the composite light-emitting layer 130 c 1. That is, the reflective first passivation layer 172 is arranged at the top of the composite light-emitting layer 130 c 1, and the light-shielding coating 117 (i.e., a light-shielding pattern) is arranged at the bottom thereof. Thus, the composite light-emitting layer 130 c 1 may be used as a light-reflecting plate of the backlight module 100 c 1 while providing a light-emitting function.

The above embodiments are described with the composite light-emitting layer separately providing the function of top-view light source or side-view light source; however, in other embodiments of the invention, both kinds of the light sources may be integrated into a single composite light-emitting layer. FIG. 5 to FIG. 7 are partial cross-sectional views of various backlight modules according to other embodiments of the invention. Similarly, the button structure is not shown in the following drawings, but it should be understood that the backlight modules below are disposed under the button structure to provide a backlit button. The same or similar components as the previous embodiments are represented by the same reference numerals in the following embodiments.

Referring first to FIG. 5, in a backlight module 100 d of the present embodiment, a composite light-emitting layer 130 d includes the film 135, and the first circuit 139, the first light source 140, and the first passivation layer 142 disposed on the film 135. The composite light-emitting layer 130 d further includes a second light source 180, a second circuit 182, and a second passivation layer 184. In the present embodiment, the film 135 is a light-transmitting substrate, and the first circuit 139, the first light source 140, the second circuit 182, and the second light source 180 are disposed on the same side surface of the light-transmitting substrate (the film 135), and the light source 140 and the second light source 180 are electrically connected to the first circuit 139 and the second circuit 182, respectively. Similar to the first passivation layer 142 covering the first circuit 139, the second passivation layer 184 covers the second circuit 182, such that at least a portion of the second circuit 185 is located between the second passivation layer 184 and the light-transmitting substrate (the film 135) to avoid damage to the circuit layout. The first light source 140 and the second light source 180 are located on the same side of the light-transmitting substrate (the film 135). The first circuit 139 and the second circuit 182 may be formed simultaneously on the film 135, and the first passivation layer 142 and the second passivation layer 184 could be disposed on the first circuit 139 and the second circuit 182 in a single step. Therefore, the first circuit 139 and the second circuit 182 may be made of the same material, and the first passivation layer 142 and the second passivation layer 184 may be the same film covering the different regions.

The first light source 140 and the second light source 180 are disposed on the surface of the film 135 that is distal to the light guide plate 120 (i.e., the upper surface of the film 135). The light-reflecting coating 136 and the light-shielding coating 137 that are collectively used as the light-shielding pattern are disposed above the first light source 140, for example. The light emitted by the first light source 140 is emitted upward and then reflected by the light-reflecting coating 136 so as to enter the light guide plate 120 and be reflected again by the reflective plate 110, until the light is emitted out from a portion of the light guide plate 120 not shaded by the light-shielding coating 137, thereby obtaining the uniform light emission over the backlight module 100 d. Since the upper portion of the second light source 180 is not shaded, the emitted light could directly travel toward a direction opposite to the light guide plate 120, thereby upward illuminating a single button. The first light source 140 is adapted to emit light toward the light guide plate 120 to provide an overall backlighting with uniformity for replacing the side-view light source; the second light source 180 is used as a top-view light source for providing independent and localized backlighting for special buttons (e.g., hot keys). The second light source 180 may include a plurality of light-emitting diodes (not shown) that emit light having different wavelengths to achieve a combination of light emission with various colors. In addition, the film 135 may further have a light-shielding pattern under the second light source 180 to further prevent the light of the second light source 180 from entering the light guide plate 120 and affecting the colored light mixing. In this way, the backlight module 100 d disposed under the button structure could deliver the even and uniform backlighting to the entire keyboard and provide a specific button with the directional backlighting via the composite light-emitting layer 130 d, thereby exhibiting various backlighting effects.

Referring to FIG. 6, the major difference between a backlight module 100 e of FIG. 6 and the backlight module 100 d of FIG. 5 is that, in the present embodiment, a light guide plate 120 e further has a plurality of microstructures 124. In detail, the microstructures 124 are separated from each other, and could be arranged on the surface of the light guide plate 120 e away from the first light source 140 and corresponding to the first light source 140, such that the optical path could be for changed to uniformly distribute the light and to directionally correct the optical effect. In an embodiment, the microstructures 124 of the light guide plate 120 e are concave-convex microstructures having a contour, for example, of a concave prism, an annular V groove, a dot, a column, a cone, a pyramid, or a combination of the above, thereby enabling the increased light refraction or scattering to take place on the lower surface of the light guide plate 120 e to change the transmission direction of the light and distribute the light uniformly. The microstructures 124 could be disposed on the lower surface of the light guide plate 120 e only at a position corresponding to the first light source 140, or could be disposed on the entire lower surface of the light guide plate 120 e. In addition, the microstructures 124 of the light guide plate 120 e may be disposed at a position corresponding to the light-transmitting character portion of the keycap, such the microstructures 124 are, for example, distributed under the opening of the bracket of the button structure to adjust the exit angle of the light, thereby illuminating the rear side of the keycap through the opening of the bracket.

Referring to FIG. 7, the major difference between a backlight module 100 f of FIG. 7 and the backlight module 100 d of FIG. 5 is that, in the present embodiment, the first light source 141 and the second light source 181 of the backlight module 100 f are disposed on the surface of the light-shielding plate 134 facing toward the light-reflecting plate 110. That is, the first light source 141, the second light source 181, and the light guide plate 120 are located on the same side of the light-shielding plate 134. The first light source 141 and the second light source 181 are disposed on the lower surface of the film 135. The light guide plate 120 has the holes 122, and the first light source 141 and the second light source 181 are disposed at the positions corresponding to the holes 122. For example, the first light source 141 and the second light source 181 are configured into the holes 122, or located on the periphery of the holes 122, so that the upper surface of the film 135 of the light-shielding plate 134 could be flat without protrusions caused by the light sources. The light-reflecting coating 136 and the light-shielding coating 137 are disposed above the first light source 141. Similarly, the light emitted by the first light source 141 is emitted upward and then reflected by the light-reflecting coating 136 to enter the light guide plate 120, and then is reflected by the reflective plate 110 again, until the light is extracted out of the light guide plate 120, thereby providing the uniform illumination. The second light source 181 that is not shaded emits the light directly and toward a direction opposite to the light-reflecting plate 110, so as to achieve the directional and independent backlighting effect for a specific button.

FIG. 8 is a partial cross-sectional view of the button structure with a backlight module according to another embodiment of the invention. Referring to FIG. 8, in the embodiment, the button structure 10 of the light-emitting keyboard 5 (marked in FIG. 1A) includes a bracket 15 with at least one opening 18, a keycap 11, a support assembly 12 and a circuit layer 14. The keycap 11 is connected to the bracket 15 via the support assembly 12. The circuit layer 14 is disposed between the keycap 11 and the bracket 15. A backlight module 200 is disposed under the bracket 15.

In the embodiment, the backlight module 200 includes a composite light-emitting layer 210 and a spacing layer 220. The composite light-emitting layer 210 includes a substrate 212, at least one light source 211 and at least one circuit 215. The substrate 212 may be a light-transmitting substrate, which is, for example, a PET substrate, but material of the substrate 212 is not limited thereto. However, in other embodiments, the substrate 212 can be a light-shielding substrate, it is not limited thereto.

The at least one light source 211 is disposed on an upper surface 213 of the substrate 212 and located under the keycap 11. In addition, the light source 211 functions as, for example, a top-view light source 211 such that light emitted from the light source 211 is transmitted upwardly to the light-transmitting portion 11 a of the keycap 11. In some embodiment, the light source 211 may be a chip-scale packaged LED or mini LED.

Moreover, the at least one circuit 215 is disposed on the upper surface 213 of the substrate 212 and electrically connected to the at least one light source 211. In some embodiments, two light sources 211 which are respectively coupled to the circuits 215 are arranged on the substrate 212. Certainly, in other embodiments, the number of the light source 211 can be one or more than two, which is not limited thereto.

As shown in FIG. 8, in the embodiment, the backlight module 200 further includes a passivation layer 216. The passivation layer 216 is disposed on the upper surface 213 of the substrate 212 and covers the circuit 215 and the light source 211, such that at least a portion of the light source 211 and the circuit 215 are located between the passivation layer 216 and the substrate 212 so as to protect both of the circuit 215 and the light source 211, thereby preventing an open circuit or a short circuit caused by the damaged circuit on the substrate 212. The passivation layer 216 is, for example, a flexible polymer film having a thickness less than the thickness of the substrate 212.

The spacing layer 220 is disposed between the composite light-emitting layer 210 and the bracket 15, wherein the spacing layer 220 includes at least one hole 224 corresponding to the at least one light source 211 and the at least one opening 18 of the bracket 15. The number of the hole 224 is, for example but not limited thereto, equal to that of the light source 211; that is, the spacing layer 220 may have two holes 224. The light sources 211 are located in the holes 224 of the spacing layer 220.

As compared with the conventional backlight module which has the side-view light source coupled to the FPC and retained in the connecting hole of the stacked light guide plate and the reflective plate from the rear side thereof, the light source 211 of the backlight module 200 is the top-view light source such that the conventional light guide plate and the through hole of the reflective plate are not required, and the thickness of the backlight module 200 can be reduced and the optical effect can be enhanced as well.

In the embodiment, an orthographic projection of the elastic body 13 projected onto the substrate 212 is not overlapped with an orthographic projection of the light source 211 projected onto the substrate 212. In other words, the light source 211 is not located directly under the elastic body 13, but could be arranged beneath the support assembly 12. In order to prevent the light source 211 being hit by the support assembly 12 (scissor-like mechanism) when the keycap 11 is pressed downwardly, the spacing layer 220 is disposed between the substrate 212 and the bracket 15. Due to the spacing layer 220, a distance between the substrate 212 and the bracket 15 becomes greater, such that the light source 211 does not protrude from a top surface of the bracket 15. Therefore, the possibility that the light source 211 is hit by the support assembly 12 when the keycap 11 is pressed downwardly can be reduced.

Specifically, the top surface of the spacing layer 220 is higher than the top surface of the light source 211. In an embodiment, a thickness T1 of the spacing layer 220 is greater than or equal to a thickness T2 of the light source 211, such that the light source 211 does not protrude from a top surface 222 of the spacing layer 220 and does not extend into the opening 18 of the bracket 15. However, the thicknesses T1 and T2 of the spacing layer 220 and the light source 211 are not limited thereto.

Moreover, in the embodiment, the backlight module 200 further includes a first light-reflecting coating 240 and a first light-shielding coating 245. The first light-reflecting coating 240 is disposed on the entire lower surface 214 of the substrate 212, and the first light-shielding coating 245 is disposed under the first light-reflecting coating 240, so that the first light-reflecting coating 240 is sandwiched between the substrate 212 and the first light-shielding coating 245. A part of light emitted from the light sources 211 and passing through the substrate 212 could be reflected upwardly by the first light-reflecting coating 240, while the first light-shielding coating 245 could prevent the light from leaking from the rear side of the backlight module 200. In an embodiment, the first light-reflecting coating 240 is a white paint, and the first light-shielding coating 245 is a black paint. The colors of the first light-reflecting coating 240 and the first light-shielding coating 245 are not limited to the disclosure.

The backlight module 200 further includes a second light-shielding coating 230 disposed on the top surface 222 of the spacing layer 220 facing to the bracket 15. The second light-shielding coating 230 is a black paint, for example. The backlight module 200 further includes an adhesive layer 260, disposed between the second light-shielding coating 230 and the bracket 15 such that the backlight module 200 can be fixed to the button structure by the adhesive layer 260.

In addition, as shown in FIG. 8, the keycap 11 includes a bottom plate 11 b and a plurality of side plates 11 c protruding from the bottom plate 11 b. FIG. 9 is a projecting view of the light source, the bracket and the first light-shielding coating projected onto the keycap of FIG. 8. It is noted that a central part 11 d (FIG. 9) of the keycap 11 is marked by a dotted line. Referring to FIG. 9, in an embodiment, a shape of the second light-shielding coating 230 is a frame shape, a projection of the light source 211 projected onto the keycap 11 is located within the central part 11 d (dotted line zone) of the keycap 11, and a projection of the second light-shielding coating 230 projected onto the keycap 11 is located out of the central part 11 d of the keycap 11 and overlaps with the side plates 11 c of the keycap 11. Because the second light-shielding coating 230 is located corresponding to a position of edges of the keycap 11, the light emitted from the light source 211 can be shielded by the second light-shielding coating 230 so as to prevent the light leakage from the edge of the keycap 11.

FIG. 10 to FIG. 15 are respectively partial cross-sectional views of the button structure with various backlight modules according to other embodiments of the invention.

Referring FIG. 10, the main difference between the backlight module 200 of FIG. 8 and the backlight module 200 a of FIG. 10 is that, in the embodiment, the backlight module 200 a further includes a second light-reflecting coating 235. The second light-reflecting coating 235 is disposed on the top surface 222 of the spacing layer 220, a projection of the second light-reflecting coating 235 projected onto the keycap 11 is located within a central part 11 d (the dotted line zone shown in FIG. 9) of the keycap 11, so that the second light-reflecting coating 235 could overlap with the bottom plate 11 b of the keycap 11 but not overlap with the side plates 11 c of the keycap 11 in a direction along the keycap 11 being pressed. The second light-reflecting coating 235 can help for reflecting light emitted from the light source 211 so as to enhance the light emitting efficiency. In addition, the second light-shielding coating 230 is stacked on a portion of the second light-reflecting coating 235 which is close to a position corresponding to the side plates 11 c of the keycap 11 so as to prevent the light leakage from the edge of the keycap 11.

Referring to FIG. 11, the main difference between the backlight module 200 of FIG. 8 and the backlight module 200 b of FIG. 11 is that, in the embodiment, a portion of the light source 211 is located within the opening 18 of the bracket 15. A thickness T3 of the spacing layer 220 b of the backlight module 200 b is, for example, less than the thickness T1 of the light source 211, such that the light source 211 protrudes out of the top surface 222 of the spacing layer 220 b and extends into the opening 18 of the bracket 15, while the top surface of the light source 211 is still lower than the top surface of the bracket 15. Accordingly, a portion of the light source 211 is accommodated in the opening 18, and the thickness of the backlight module 200 b can be further reduced. In an embodiment, the light source 211 arranged within the opening 18 may not protrude over a half of the thickness of the bracket 15.

Referring to FIG. 12, the main difference between the backlight module 200 of FIG. 8 and the backlight module 200 c of FIG. 12 is that, in the embodiment, the spacing layer 220 c of the backlight module 200 c is a light-shielding plate, for example, an Mylar plate. The color of the spacing layer 220 c is black or dark-colored such that the second light-shielding coating 230 of the backlight module 200 (as elaborated in FIG. 8) is no longer required, such that the overall thickness of the backlight module 200 c can be reduced. The second light-reflecting coating 235 is disposed on the top surface 222 of the opaque spacing layer 220 c so as to reflect light upwardly. A projection of the second light-reflecting coating 235 projected onto the keycap 11 is located in a central part 11 d of the keycap 11. That is, at least a portion of the spacing layer 220 c is not covered by the second light-reflecting coating 235.

Referring to FIG. 13, the main difference between the backlight module 200 of FIG. 8 and the backlight module 200 d of FIG. 13 is that, in the embodiment, the spacing layer 220 d of the backlight module 200 d is a light guide plate. The second light-reflecting coating 235 is disposed on a portion of the top surface 222 of the spacing layer 220 d at positions corresponding to the edges of the keycap 11 (for example, the side plates 11 c of the keycap 11), and the second light-shielding coating 230 is stacked on the second light-reflecting coating 235. The other portion (a central portion) of the top surface 222 of the spacing layer 220 d corresponding to a position of the central part 11 d (i.e., the dotted line zone shown in FIG. 9) of the keycap 11 is exposed without being shielded by the second light-reflecting coating 235 or the second light-shielding coating 230, such that light emitted from the light source 211 is capable of passing through the other portion (the central portion) of the top surface 222 of the spacing layer 220 d and emitted upwardly to the keycap 11. In some embodiments, a portion of the second light-reflecting coating 235 close to the light source 211 is not covered by the second light-shielding coating 230; that is, the second light-reflecting coating 235 could partially protrude from an edge of the frame-shaped light-shielding coating 230, thereby enhancing the luminance corresponding to a specified spot.

It is noted that the backlight module 200 d further includes a plurality of microstructures 226 arranged on the bottom surface of the spacing layer 220 d, such that the optical path of the light emitted from the light source 211 could be modified so as to uniformly distribute the light and to directionally correct the optical effect. In an embodiment, the microstructures 226 are concave or convex microstructures having a contour, for example, of a concave prism, an annular V groove, a dot, a column, a cone, a pyramid, or a combination of the above, thereby enabling the increased light refraction or scattering to take place on the bottom surface of the light guide plate to change the transmission direction of the light and distribute the light uniformly.

Referring to FIG. 14, the main difference between the backlight module 200 d of FIG. 13 and the backlight module 200 e of FIG. 14 is that, in the embodiment, the microstructures 226 of the backlight module 200 e are arranged on the top surface 222 of the spacing layer 220 e. The microstructures 226 are, for example, arranged at the position corresponding to the central part 11 d of the keycap 11. Similarly, the optical path of the light emitted from the light source 211 could be modified, so as to uniformly distribute the light and to directionally correct the optical effect.

Referring to FIG. 15, the main difference between the backlight module 200 b of FIG. 11 and the backlight module 200 f of FIG. 15 is that, in the embodiment, the spacing layer 220 f is an encapsulation layer made of a transparent or translucent resin, such as epoxy resins or UV inks. The spacing layer 220 f could be fabricated by printing or pouring a liquid polymeric material and then curing the material into a solid encapsulation. As shown in FIG. 15, the spacing layer 220 f is disposed on the upper surface 213 of the substrate 212 and covers the circuit 215 on the upper surface 213 of the substrate 212 and a lower part of lateral sides of the light source 211, such that the light source 211 can be fixed to the substrate 212 firmly by the spacing layer 220 f. In the embodiment, the passivation layer 216 is disposed on the spacing layer 220 f and the light source 211, and the light source 211 extends into the opening 18 of the bracket 15. In other embodiments, as the spacing layer 220 f further covers the entire light source 211 as well as the circuit 215 for protection, the spacing layer 220 f could function as both of the encapsulation layer and the passivation layer, and therefore, the additional passivation layer 216 is not required anymore.

FIG. 16 to FIG. 17 are partial cross-sectional views of various backlight modules according to other embodiments of the invention. Referring to FIG. 16 first, in the embodiment, the backlight module 200 g further includes a connection tail 250 that might be coupled to an edge of the composite light-emitting layer 210. The connection tail 250 is partially disposed on the substrate 212 and electrically connected to the circuit 215. The connection tail 250 may include a polymer film with a circuit layer thereon, wherein the circuit layer could be a printed conductive paste or a patterned metal layer, such as printed silver wiring or a patterned copper foil, but it is not limited thereto. In an embodiment, the circuit 215 of the composite light-emitting layer 210 and the circuit layer of the connection tail 250 are made of materials with different conductivities or of different conductors. The circuit layer of the connection tail 250 may face the circuit 215 on the substrate 212, so that the connection tail 250 could be electrically coupled to the circuit 215 through a conductive adhesive 252 (for example, ACF or hotbar soldering) therebetween. The connection tail 250 can extend outwardly to an outer system (not shown) or the power supply (not shown), such that the light source 211 can be electrically connected to the outer system or the power supply through the connection tail 250. In an embodiment, the connection tail 250 can then be inserted into a connector or connected to an external circuit board of another device.

Referring to FIG. 17, in the embodiment, the connection tail 250 h of the backlight module 200 h is a flexible or foldable connection tail, which could be folded from the upper surface 213 of the substrate 212 to the lower surface 214 of the substrate 212 so as to reduce the dimension of width or length of the backlight module 200 h. In that case, the folded connection tail 250 h may allow for more flexibility in the design of the backlight module 200 h.

FIG. 18 is a projecting view of the light source, the first circuit, the second circuit and the first light-shielding coating projected onto the keycap of the button structure with a backlight module according to another embodiment of the invention. FIG. 19 is a partial cross-sectional view along A-A section of the light source, the first circuit, the second circuit of FIG. 18. It is noted that a central part 11 d of the keycap 11 in FIG. 18 is marked by a dotted line.

Referring to FIGS. 18 and 19, in the embodiment, the composite light-emitting layer 210 i of the backlight module 200 i includes the light source 211, a first circuit 217 and a second circuit 218. As shown in FIG. 19, the circuit 215 electrically connected to the light source 211 includes the first circuit 217 and the second circuit 218. The light source 211, the first circuit 217 and the second circuit 218 are covered and protected by the passivation layer 216. With reference to FIGS. 18 and 19, the first circuit 217 is electrically connected to the light source 211 and corresponds to the position of the central part 11 d of the keycap 11. The second circuit 218 is electrically connected to the first circuit 217 and extended outwardly and along the orthographic projection of the two opposite side plates 11 c of the keycap 11. The extended second circuit 218 may be further coupled to another light source and the corresponding circuit that are arranged under another keycap adjacent to the keycap 11. In some embodiments, a material of the first circuit 217 is different from a material of the second circuit 218, and a width of the first circuit 217 is less than a width of the second circuit 218. The first circuit 217 and the second circuit 218 may be made of materials with different conductivities. The first circuit 217 is, for example, made of a conductive component that could provide the improved adhesion to the light source 211, as compared with the second circuit 218.

Based on the above, the backlight module and the light-emitting keyboard of the invention includes the light source located under the keycap, and the light source is located in the hole of the spacing layer, so that the light source and the spacing layer are located at the same level, the light-emitting keyboard and the backlight module could be miniaturized in thickness. In addition, because light emitted from the light source is transmitted upwardly to the keycap, the optical path of the light source directly illuminate the button structure to provide a localized backlighting effect to the individual buttons.

Lastly, it should be mentioned that: each of the above embodiments is only used to describe the technical solutions of the invention and is not intended to limit the invention; and although the invention is described in detail via each of the above embodiments, those having ordinary skill in the art should understand that: modifications may still be made to the technical solutions recited in each of the above embodiments, or portions or all of the technical features thereof may be replaced to achieve the same or similar results; the modifications or replacements do not make the nature of corresponding technical solutions depart from the scope of the technical solutions of each of the embodiments of the invention. 

What is claimed is:
 1. A light-emitting keyboard, comprising: a bracket having an opening; a keycap disposed on the bracket and connected to the bracket via a support assembly; a circuit layer disposed between the keycap and the bracket; a composite light-emitting layer disposed under the bracket, comprising: a substrate; a circuit disposed on the substrate; a reflective passivation layer covering the circuit; and a light source located under the keycap and electrically connected to the circuit, wherein light emitted from the light source is transmitted to the keycap; and a spacing layer disposed between the composite light-emitting layer and the bracket, wherein the spacing layer comprises a hole corresponding to the opening of the bracket, and the light source is located in the hole of the spacing layer.
 2. The light-emitting keyboard of claim 1, wherein a top surface of the spacing layer is higher than a top surface of the light source.
 3. The light-emitting keyboard of claim 1, wherein a top surface of the light source is located within the opening, and the top surface of the light source is lower than a top surface of the bracket.
 4. The light-emitting keyboard of claim 1, further comprising a first light-reflecting coating and a first light-shielding coating, the substrate is a light-transmitting substrate, the light source and the circuit are disposed on an upper surface of the substrate, the first light-reflecting coating is disposed on a lower surface of the substrate, and the first light-shielding coating is disposed under the first light-reflecting coating.
 5. The light-emitting keyboard of claim 1, further comprising a second light-shielding coating disposed between the spacing layer and the bracket, wherein the keycap comprises a bottom plate and a plurality of side plates protruding from the bottom plate, the second light-shielding coating is a frame shape corresponding to the side plates of the keycap.
 6. The light-emitting keyboard of claim 5, further comprising a second light-reflecting coating disposed on a top surface of the spacing layer, wherein the second light-shielding coating is disposed on a portion of the second light-reflecting coating, the second light-reflecting coating is surrounded by the second light-shielding coating.
 7. The light-emitting keyboard of claim 1, wherein the spacing layer is a light-shielding plate, a second light-reflecting coating is disposed on a top surface of the spacing layer, and the second light-reflecting coating is located within a coverage of the keycap.
 8. The light-emitting keyboard of claim 1, wherein the spacing layer is a light guide plate, and a plurality of microstructures is arranged on a surface of the spacing layer.
 9. The light-emitting keyboard of claim 1, wherein the spacing layer is an encapsulation layer, and the reflective passivation layer is disposed on the spacing layer.
 10. The light-emitting keyboard of claim 1, further comprising a foldable connection tail, wherein the foldable connection tail is partially disposed on the substrate and electrically connected to the circuit.
 11. The light-emitting keyboard of claim 10, wherein the connection tail comprises a circuit layer facing the circuit of the composite light-emitting layer and being made of a material with a different conductivity from the circuit, and the circuit layer is electrically coupled to the circuit through a conductive adhesive.
 12. The light-emitting keyboard of claim 1, wherein the circuit comprises a first circuit electrically connected to the light source and a second circuit electrically connected to the first circuit and coupled to another light source corresponding to an adjacent keycap, and a material of the first circuit is different from a material of the second circuit.
 13. A backlight module adapted to be disposed under a button structure, wherein the backlight module comprises: a composite light-emitting layer comprising a substrate, a light source and a first circuit disposed on a first side of the substrate, and a reflective passivation layer covering the first circuit and the substrate, wherein the light source is coupled to the first circuit, and light emitted from the light source is adapted to be transmitted to the button structure; and a spacing layer disposed on the composite light-emitting layer, wherein the spacing layer comprises a hole, and the light source is located in the hole of the spacing layer.
 14. The backlight module of claim 13, wherein a thickness of the spacing layer is greater than or equal to a thickness of the light source.
 15. The backlight module of claim 13, wherein a thickness of the spacing layer is less than a thickness of the light source such that a portion of the light source extends into an opening of the button structure.
 16. The backlight module of claim 13, further comprising a first light-reflecting coating and a first light-shielding coating disposed on a second side of the substrate, wherein the first light-reflecting coating is arranged between the first light-shielding coating and the substrate.
 17. The backlight module of claim 13, further comprising a second light-shielding coating disposed on a top surface of the spacing layer facing the button structure, wherein a shape of the second light-shielding coating is a frame shape exposing the light source.
 18. The backlight module of claim 13, further comprising a second light-reflecting coating and a second light-shielding coating, wherein the second light-reflecting coating is disposed on a top surface of the spacing layer, the second light-shielding coating is disposed on the top surface of the spacing layer and stacked on a portion of the second light-reflecting coating, a shape of the second light-shielding coating is a frame shape, at least a portion of a projection of the second light-reflecting coating projected onto the spacing layer overlaps with a projection of the second light-shielding coating projected onto the spacing layer.
 19. The backlight module of claim 13, wherein the spacing layer is a light-shielding plate, a second light-reflecting coating is disposed on a top surface of the spacing layer, and a projection of the second light-reflecting coating is located adjacent to the hole.
 20. The backlight module of claim 13, wherein the spacing layer is a light guide plate, and a plurality of microstructures is arranged on a top surface or a bottom surface of the spacing layer.
 21. The backlight module of claim 13, wherein the spacing layer is an encapsulation layer made of a transparent or translucent resin.
 22. The backlight module of claim 13, wherein the composite light-emitting layer further comprises a second circuit electrically connected to the first circuit and extended outwardly, wherein the first circuit and the second circuit are made of materials with different conductivities.
 23. The backlight module of claim 22, further comprising a connection tail, wherein the connection tail is partially disposed on the substrate and electrically connected to the second circuit through a conductive adhesive, and the connection tail is folded from an upper surface of the substrate to a lower surface of the substrate.
 24. The light-emitting keyboard of claim 1, further comprising a connection tail electrically connected to the circuit, wherein the connection tail extending from the substrate is flexible or foldable.
 25. The light-emitting keyboard of claim 1, further comprising a light-shielding coating disposed between the spacing layer and the bracket at a position corresponding to the light source. 